Retroviral infections are a serious cause of disease, most notably, the acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus (HIV) has been recognized as the etiologic agent of AIDS and compounds having an inhibitory effect against HIV multiplication have been actively sought.
Mitsuya et al., "3'-Azido-3'-deoxythymidine (BW A509U): An antiviral agent that inhibits the infectivity and cytopathic effect of human T-lymphotropic virus type III/lymphadenopathy-associated virus in vitro", Proc. Natl. Acad. Sci. U.S.A., 82, pp. 7096-7100 (1985), refers to a compound of formula (A) (3'-azido-2'3'-dideoxythymidine), commonly referred to as AZT. This compound is said to be useful in providing some protection for AIDS carriers against the cytopathogenic effect of immunodeficiency virus (HIV). ##STR1##
Mitsuya et al., "Inhibition of the in vitro infectivity and cytopathic effect of human T-lymphotrophic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) by 2'3'-dideoxynucleosides", Proc. Natl. Acad. Sci. U.S.A., 86, pp. 1911-15 (1986), have also referred to a group of 2',3'- dideoxynucleosides shown in Formula (B) which are said to possess protective activity against HIV-induced cytopathogenicity. ##STR2##
Balzarini et al., "Patent and selective anti-HTLV-III/LAV activity of 2',3'-dideoxycytidinene, the 2',3'-unsaturated derivative of 2',3'-dideoxycytidine", Biochem. Biophys. Res. Comm., 140, pp. 735-42 (1986), refer to an unsaturated analogue of these nucleosides--2'3'-dideoxy-cytidine, shown in Formula (C)--as being characterized by antiretroviral activity. ##STR3##
Baba et al., "Both 2',3'-dideoxythimidine and its 2',3'-unsaturated derivative (2',3'-dideoxythymidinene) are potent and selective inhibitors of human immunodeficiency virus replication in vitro", Biochem. Biophys. Res. Comm., 142, pp. 128-34 (1987), refer to the 2',3'-unsaturated analogue shown in Formula (D) of 2',3'-dideoxythymidine. This analogue is purported to be a potent selective inhibitor of HIV replication. ##STR4##
Analogues of AZT known as 3'-azido-Z', 3'-dideoxyuridine shown in Formula (E), where bromine or iodine have been said to have an inhibitory activity against Moloney murine leukemia in T. S. Lin et al., "Synthesis and antiviral activity of various 3'-azido, 3' amino, 2',3'-unsaturated and 2',3'-dideoxy analogues of pyrimidine, deoxyribonucleosides against retroviruses", J. Med. Chem., 30, pp. 440-41 (1987). ##STR5##
Finally, the 3'-fluoro analogues of 2',3'-dideoxycytidine shown in Formula (F) and of 2',3'-dideoxythymidine shown in Formula (G) are referred to in Herdewijn et al., "3'-Substituted 2',3'-dideoxynucleoside analogues as potential anti-HIV(HTLV-III/LAV) agents", J. Med. Chem., 30, pp. 1270-78 (1987), as having potent antiretroviral activity. ##STR6##
The most potent anti-HIV compounds thus far reported are 2',3'-dideoxynucleosides, more particularly, 2',3'-dideoxy cytidine (ddCyd) and 3'-azido-2',3'-dideoxythymidine (AzddThd or AZT). These compounds are also active against other kinds of retroviruses such as the Moloney murine leukemia virus. Because of the increasing incidence and the life-threatening characteristics of AIDS, efforts are being expended to discover and develop new nontoxic and potent inhibitors of HIV and blockers of its infectivity. It is therefore an object of the present invention to provide effective anti-HIV compounds of low toxicity and a synthesis of such new compounds that is readily feasible.